Straight Axle W/Coil overs and triples - Help

[Lil' Rich]

I noticed that a lot of the rock crawling and rock racing guys can learn a bit from the desert guys. So when I decided to put together a vehicle for Rock Racing and Desert Racing, I figured that maybe you guys could help.

I am running a straight axle front and rear with coil overs and triple bypasses on all four corners. I planned on running the rear shock set ups up the links by about 1/3 of the link length. I have 16" coil overs and 18" Triples for the rear and 16" coil overs and 14" triples for the front.

I was planning on running the coil overs in front of each bypass shock.

I realize with a front straight axle I will be fighting a lot of jolts, my biggest question is how can I get the best set up for the front axle so I can hit the bumps fast?

Thanks for your time,

Lil' Rich

[camo]

Rich,

I am building a rockcrawler for prerunning as well and I am using 14" coilovers and 14" triples at each corner. it is a huge challenge to make a rock rig desert capable because you are asking it to do 2 diffrent things so at best you will have a compromise. I am not sure I could truley answer your question on the BB but if you want to get together and have a long debate/conversation over the design ideas and how we came up with what were doing I would be happy to help.

FYI ...I am building a Hendrix X chassis with the James Link front and rear 4 link setup. However Mike Shaffer and crew have modified the hendrix setup extensively to better suit it for the dual purpose.

[Brutpwr]

You can go surprisingly fast with the setup you have once you get it dialed in. There are two CORR Pro 4 trucks running solid axles front and rear and they get it on! You have to remember that the CORR trucks run 100% all out as fast as you can go since the races are shorter. When the desert trucks come on the track they are much slower as they are much taller and heavier. Since you are building a rock rig/race rig it will be lighter and lower so it should work well. I'm guessing you may want to switch your front and rear bypass shocks and use the longer ones up front as the front ones will be running closer to 1:1 I would think because of space limitations. Just run the rear ones up in front of the coilovers on the links and limit down travel so you don't top out the shorter shock.

Jason

[Lil' Rich]

Thanks guys, I can definitely change shock set-ups if need be. CAMO, I'll take you up on that offer, I'll be in Placerville Tuesday and Wednesday if you wanna catch up.

Any other ideas? I was thinking links angles maybe aswell. I heard that I'll want my lower links as flat as possible when running the desert so it is easier to move the axle vertical. Is this true?

I figured I would have to dial the vehicle in for each race, Kinda like going from Short course to Desert...

[MIKE S]

Originally Posted by Lil' Rich

I noticed that a lot of the rock crawling and rock racing guys can learn a bit from the desert guys. So when I decided to put together a vehicle for Rock Racing and Desert Racing, I figured that maybe you guys could help.

I am running a straight axle front and rear with coil overs and triple bypasses on all four corners. I planned on running the rear shock set ups up the links by about 1/3 of the link length. I have 16" coil overs and 18" Triples for the rear and 16" coil overs and 14" triples for the front.

I was planning on running the coil overs in front of each bypass shock.

I realize with a front straight axle I will be fighting a lot of jolts, my biggest question is how can I get the best set up for the front axle so I can hit the bumps fast?

Thanks for your time,

Lil' Rich

The key is in the setup!

Most rock rigs have 75% down travel, And that will never ever work for going fast! On most gofast trucks are set up with 60 to 75% up travel and they run a lot more spring rate

Camo's rig at ride height will have 10" up in the rear and 8 in the front with a 20" high belly. Is was set up with 7 in the rear and 5 in the front. It should work well but the unsprung weight is the killer! With that 60 in the front it will ride like a old CJ5 is the bumps

[Lil' Rich]

I have 35 spline Diamond Axle 9's front and rear, gonna truss the shit out of them just in case. I did plan for the mega amounts of up travel compared to the rock crawlers. I was planning on 12 of up in front and around 16-18 in the rear.

The killer thing I was thinking about is having a front engine. I have the LS2 going in but Ithink all that weight right above (and a little behind) the front axle will cause some good jolts (which I am hoping the triple bypasses take care of)

[jamesjones]

Here's how Nate(Blitzkrieg) did my Blazer(radius arm/panhard). I don't think it would handle the rocks all that well though.



It handles great for desert duty though.

[jamesjones]

On the bumps


Full droop

[Nordic1]

nice

[fabtoys]

Which one or whatever you build ,use chromoly for all your suspension arms or you'll be sorry Big rich get a hold of greg hosmann he can give you a lot of feed back i can PM his number if needed

[revor]

Some useful information while being very different might be had looking around for information regarding this. http://www.outback4x4challenge.com/
I was a competitor in the 2006 and it was some of the most challenging terrain I'd ever seen... The trucks are designed to be truely multi purpose and bring in tech from UROK to SCORE. Most ran coilovers and about half ran Bypass shocks, all of them ran live front axles and the vast majority ran radius arms and linked rear suspensions in some form or another.

[BrettM]

on that Blazer, is that 1 poly bushing and 1 heim on each radius arm (axle side)? do you run a swaybar?

[CA_YJ]

I'm doing something very similar to what you are talking about. I't is very tricky to get the best of both worlds and compromise is inevitable. With that said I am focusing on rear travel. With the help of a friend who is a CAD GOD, I'm drawing everything...I can get 22" of travel out of a 14" coilover in the rear...the problem you will run into is that desert rigs run bushings on one end to keep the arm from flopping around. Rock crawlers need flexable joints on both ends. Anyone who says bushings flex enough is just flat out wrong (if you want unrestricted flex for rock crawling).

So in order to run the coilover and bypass off the link you have to make a stibilizer link that is mounted at a calculated angle off the lower link (trailing arm) This is tricky...

One more thing to consider. The hiem on a coilover doesn't have enough flex in it to be mounted the same way desert trucks do it. So mounting gets a bit creative. I don't have a pic with me but the lower mounting bolt has to run parallel to the trailing arm, not perpendicular like desert trucks do. Basically if you want it to flex on the rocks without binding its a total headache. Tough to do, but it can be done. I'll try to get some pics of what I mean next week as I'm putting together my rear suspension on my buggy.

[tsm1mt]

Originally Posted by CA_YJ

So in order to run the coilover and bypass off the link you have to make a stibilizer link that is mounted at a calculated angle off the lower link (trailing arm) This is tricky...

Or you design your links so the coilover mounts BELOW the center line of the link (from heim to heim) and it won't flop over.

The bushing is used because the link wasn't designed to mount the coilover below the center line, and that's the only way to keep the link from flopping.

[Lil' Rich]

Originally Posted by tsm1mt

Or you design your links so the coilover mounts BELOW the center line of the link (from heim to heim) and it won't flop over.

The bushing is used because the link wasn't designed to mount the coilover below the center line, and that's the only way to keep the link from flopping.

This is what I was planning on doing and I am fairly ceretain I can get enough travel on the rear.

But what about the front? I heard that the more the lower links are to horizontal the better off I am. I would like to have the front axle travel vertical easier than most rock crawlers as it's all about uptravel in desert racing. So any recommendations on easing the upward motion of the front axle?

[tsm1mt]

Originally Posted by Lil' Rich

This is what I was planning on doing and I am fairly ceretain I can get enough travel on the rear.

But what about the front? I heard that the more the lower links are to horizontal the better off I am. I would like to have the front axle travel vertical easier than most rock crawlers as it's all about uptravel in desert racing. So any recommendations on easing the upward motion of the front axle?

What makes the front travel "easier" vertically?

You want more up-travel from ride height, of course.

The rest should just be valving and spring rate as to how "easy" it moves.

What you probably want to set things up for would be "horizontal radius arms" and "horizontal track bar" when you're at the mid-point of your front travel to minimize the changes as the suspension cycles.

The dilemma is if you mount the RA too high on the axle, you'll limit uptravel when the radius arm hits the frame. You'll also have issues with the trackbar clearing things at full bump, too, unless it's actually forward of the frame and engine - then it'd be no problem.

Of course, it'd also be vulnerable to damage..

[Lil' Rich]

Originally Posted by tsm1mt

What makes the front travel "easier" vertically?

You want more up-travel from ride height, of course.

The rest should just be valving and spring rate as to how "easy" it moves.

What you probably want to set things up for would be "horizontal radius arms" and "horizontal track bar" when you're at the mid-point of your front travel to minimize the changes as the suspension cycles.

The dilemma is if you mount the RA too high on the axle, you'll limit uptravel when the radius arm hits the frame. You'll also have issues with the trackbar clearing things at full bump, too, unless it's actually forward of the frame and engine - then it'd be no problem.

Of course, it'd also be vulnerable to damage..

luckily i think we can eliminate a lot of framee hihtting and such due to the tube chassis (building to W.E.ROCK pro modified rules). so with werock's rules as a base, i can have full hydro and and a tube chassis.

since it looks like I won't be running a steering box, do you think a triangulated four link would work better than an RA/track bar setup?

[CA_YJ]

Originally Posted by tsm1mt

Or you design your links so the coilover mounts BELOW the center line of the link (from heim to heim) and it won't flop over.

The bushing is used because the link wasn't designed to mount the coilover below the center line, and that's the only way to keep the link from flopping.

Cool idea, but wouldnt it have to hang pretty far below the centerline of the link?? This would be pretty tough to build I would think.

[tsm1mt]

Originally Posted by CA_YJ

Cool idea, but wouldnt it have to hang pretty far below the centerline of the link?? This would be pretty tough to build I would think.

The biggest issue for "us" is usually that it hangs low enough to become a rock magnet, but it's not hard to build - desert racers have for years.

Check out Giant's DIY 4-link kit.





On second thought, looks like they might not have sunk the shock mounts as low as they should be - but just sink 'em down a little more and you're set.

Either build the top not-quite-straight (put a bow in the top plate), or build the arms "wide" so the coil fits down into the mount pocket, or just run the extended eyes they sell for just this purpose that would lower the shock eye an inch or two below where the coil cup normally would be, so you can fit it inside your trailing arm.

[powdr7]

Originally Posted by CA_YJ

I'm doing something very similar to what you are talking about. I't is very tricky to get the best of both worlds and compromise is inevitable. With that said I am focusing on rear travel. With the help of a friend who is a CAD GOD, I'm drawing everything...I can get 22" of travel out of a 14" coilover in the rear...the problem you will run into is that desert rigs run bushings on one end to keep the arm from flopping around. Rock crawlers need flexable joints on both ends. Anyone who says bushings flex enough is just flat out wrong (if you want unrestricted flex for rock crawling).

So in order to run the coilover and bypass off the link you have to make a stibilizer link that is mounted at a calculated angle off the lower link (trailing arm) This is tricky...

One more thing to consider. The hiem on a coilover doesn't have enough flex in it to be mounted the same way desert trucks do it. So mounting gets a bit creative. I don't have a pic with me but the lower mounting bolt has to run parallel to the trailing arm, not perpendicular like desert trucks do. Basically if you want it to flex on the rocks without binding its a total headache. Tough to do, but it can be done. I'll try to get some pics of what I mean next week as I'm putting together my rear suspension on my buggy.

Let's get the pics going here! Im working on building something pretty much the same, go fast rock crawler.

Rich we'll have to talk and see what some ideas each one of us have.

[mustange70]

If you wanna build a go fast rock buggy heres a good one to model it after:
http://evolutionmachine.com/index.php?showtopic=875

[Lil' Rich]

Originally Posted by mustange70

If you wanna build a go fast rock buggy heres a good one to model it after:
http://evolutionmachine.com/index.php?showtopic=875

I have met Clayton and he competed in our World Championships in Las Vegas. He is a really cool guy and the rig works great!

[mustange70]

yeah he's a great guy for sure, a nice thing is that i'm only a 10-15minute drive away from their shop, but that guy knows how to build a rig.

[JESSE_at_TLT]

I'm stoked to hear that so many people are thinking along these lines. I'd suggest using 16-18" long shocks and mounting them 1:1 up front. Like someone else already mentioned, it will make packaging a lot easier and that should be plenty of wheel-travel if it's set up right. I'd also recommend mounting the bypass shocks closer to the axle on both ends (instead of behind the coil-overs). The bypasses are going to be more effective if they're run closer to the axle, so you can put more valving into them.

[CA_YJ]

Originally Posted by powdr7

Let's get the pics going here! Im working on building something pretty much the same, go fast rock crawler.

Rich we'll have to talk and see what some ideas each one of us have.

Whatup Alex...

I just got back from a Vegas last night...Heading out to the shop tomorrow to keep workin on my buggy. I'll shoot some pics.